The present invention relates to lighting systems. More particularly, the present invention provides for a light tube that installs over conventional bulbs, such as fluorescent lamp bulbs.
Fluorescent lighting is commonly used in commercial, office, and residential settings in a wide variety of configurations. For example, offices are often provided with multiple forms of fluorescent lighting, including overhead lighting fixtures, cabinet and shelf lighting, and task lighting. Ideally, these different types of lighting should provide efficient, comfortable, glare-free lighting to all surfaces used by office workers, particularly those surfaces where people may be reading or writing. However, it can be difficult to provide glare-free illumination from a linear light source such as a fluorescent bulb. The need to provide high-quality lighting can also be complicated by a desire to maximize the efficiency of each lighting system.
To address these concerns, various methods have been developed for modifying the light emitted by fluorescent bulbs. For example, a fluorescent light fixture may be fitted with a light reflectors or deflectors of various forms that direct the light away from the fixture itself and toward the room and work surfaces. In this way, a larger percentage of the light emitted by the bulbs can be utilized, thereby increasing the efficiency of the lamp.
Another means of modifying light emissions is through the use of light polarizers which take advantage of the fact that light may be resolved into two orthogonal components, one of which vibrates parallel to a work surface and the other of which vibrates perpendicular to a work surface. Linear light polarizers can reduce glare by only allowing a certain component of emitted light to pass through the polarizing filter to a work surface. More specifically, these light polarizers can be used to allow mainly the perpendicular vibrating component of the light to reach a work surface, which is the portion of the light that penetrates into a task and returns to the eye carrying information about the task itself (such as color, contrast, etc.). At the same time, the light polarizer can eliminate or limit the amount of the parallel polarized portion of a light that reaches a work surface, which is the portion that bounces off a task and causes the spectral or reflective glare perceived by the eye. Thus, it is often desirable to use linear polarizers, such as reflective polarizers, between the light and the work surface so that only the more desirable vertically polarized light reaches the work surface. Suitable multilayer reflective polarizers are described, for example, in U.S. Pat. Nos. 5,882,774; 5,962,114; 5,486,949; and 5,612,820, in PCT publications WO 95/27919, 95/17691, and 97/01440, and in U.S. patent application Ser. No. 09/126,917. Suitable continuous-disperse phase reflective polarizers are described, for example, in U.S. Pat. Nos. 5,825,543, 5,867,316 and 5,751,388, in PCT publications WO 97/32225 and 99/36812, and in U.S. patent application Ser. No. 09/127,314.
Fluorescent bulbs may also be provided with protective shields to protect persons from injury in the event of tube breakage. For example, the food service industry commonly uses protective shields over fluorescent bulbs in areas where glass breakage could contaminate food products. These protective shields may include a transparent or translucent rigid plastic sleeve that is slid over a fluorescent bulb before installing the bulb in a fixture. The bulb is typically sealed in the sleeve with rigid end caps through which electrical bulb contacts can protrude for installation into a fixture. While this method of installing sleeves can provide the desired protection, the installation process can be cumbersome and time-consuming since it requires that the bulb be removed from the fixture before the sleeve can be installed. However, these sleeves are not typically designed for use with polarizing films or other means of modifying light emissions from fluorescent bulbs.
Other sleeves that are not necessarily used for protection or safety may also be installed over various types of bulbs for other purposes. For example, a sleeve can be used that filters out ultraviolet light or modifies the color of output light. Sleeves of this type are typically used to keep objects upon which the light falls from fading due to exposure to ultraviolet light, or to change the mood of a room through the use of various colored lights. There is, however, a need for light sleeves or covers that can be easily installed in light fixtures without necessarily removing the light bulb from the fixture.
In one aspect of this invention a light tube is provided for use over a light element, wherein the light tube comprises an elongated, generally tubular body having a first end, a second end, a length between the first and second ends, and a longitudinal axis extending from the first end to the second end, a longitudinal slot extending generally parallel to the longitudinal axis from the first end to the second end of the body, the slot having a first side and a second side, and at least a first notch adjacent the longitudinal slot, wherein the first notch extends from the first end of the body toward the second end of the body on one of the sides of the longitudinal slot.
The present invention also includes within its scope a light tube that further comprises a second notch adjacent the longitudinal slot, wherein the second notch extends from the first end of the body toward the second end of the body on the other side of the longitudinal slot. The first notch and second notch may be symmetrical about the first and second sides of the longitudinal slot, and the first side of the slot may be spaced from the second side of the slot.
The tubular body may further comprise an interior portion and the tube may include a first flange extending from the first side of the slot toward the interior portion of the body along the length of the body to form a first channel between the body and the first flange. Similarly, the tube may further comprise a second flange extending from the second side of the slot toward the interior portion of the body along the length of the body to form a second channel between the body and the second flange. The tube may further include a film sheet having a first end and a second end, wherein the first end of the film is positioned in the first channel and the second end of the film is positioned in the second channel.
Also provided is a light system comprising a light element and a light tube at least partially surrounding the light element, wherein the light tube comprises an elongated, generally tubular body having a first end, a second end, a length between the first and second ends, and a longitudinal axis extending from the first end to the second end, a longitudinal slot extending generally parallel to the longitudinal axis from the first end to the second end of the body, the slot having a first side and a second side, and at least a first notch adjacent the longitudinal slot, wherein the first notch extends from the first end of the body toward the second end of the body on one of the sides of the longitudinal slot.